Small digital cameras have become so inexpensive as to be offered on a wide range of portable and wearable devices from watches, to helmets, to computing tablets, to media players to cellular telephones of all kinds. Typical digital sensors have many limitations in the quality of the images that they can produce for still and video photography. Further limitations stem from the limits in digital camera cost and size. Image sensors suffer from noise in the captured images and the problem is greater with smaller image sensors. The noise is generated by the circuitry supporting each photodetector during image capture. The larger the signal from captured photons, the smaller the noise signal in comparison. The noise is relatively higher for smaller photodetectors that produce a smaller signal and for darker scenes that produce less light.
In many cases, it is possible to distinguish the noise from the image, but an accurate determination is slow and processor intensive. Many different de-noising techniques have been developed to remove noise from an image quickly before the image is stored or displayed. Some of these techniques are also suitable for a sequence of video frames and operate as the video is being recorded. One such fast technique is to blur the image. With video, images can be compared. If the noise is different for two sequential frames but the scene is not or if the scene is largely the same, then the noise can be identified and removed.